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ASME cal block sizes for piping
ASME cal block sizes for piping
In ASME PVPC 2004 Sec V Art 4, there are very stringent requirements for piping calibration blocks.
“The basic calibration block shall be
a section of pipe of the same nominal
nominal size and schedule”
(T-434.3)
This requires a very large inventory of calibration blocks to cover all possible pipe sizes.
The requirement is applied only to pipes. The paragraphs for non-piping allow specified ranges for cal block curvature (T-434.1.7) and thickness (T-434.2.3).
The previous edition of the code, PBVC 2001 Sec V Art 5, allowed a range of thicknesses (T-542.2.1) and a range of surface curvatures (T-542.3.4 and T-542.3.5) for piping calibration blocks. During the re-write of Articles 4 and 5, when weld examination became consolidated into Article 4, the range of value paragraphs were removed from piping and became applicable only to non-piping.
I’d be glad to hear any comments on this. What was the reason for the change? And does anyone else have a problem with the tight requirements? (Or are they mainly just ignoring them?)- 1 Reply
A thought-provoking and interesting post affecting practical NDT from you, David.
I wonder why the ASME Code is so much more restrictive than European Standards. Europe allows the use of flat blocks when testing girth welds. I suppose this is on the basis that, when parallel scanning, curvature is only an issue on very small OD’s when even a miniature angle probe may rock. Blocks may contain either 3mm side-drilled or 1 – 3mm flat-bottomed holes or 1mm notches. I think there is a thickness and material range which I cannot remember off-hand and I do not have the standards in front of me.
I think that the ASME requirements are often only paid lip-service. The Code is used worldwide throughout the oil & gas sectors as it is referenced by other US codes apart from BPV such as B31.3. Its not like ASME U-stamped vessels where an AI will be involved and will presumably check the blocks availability and (presumed) use. Where several remote piping fabricators are contracted ensuring conformance is made difficult by the Code, exacerbated by the Article 4 revision.
Has anybody run a sensitivity comparison between ASME and EN requirements? Surely they must be comparable. But entrencehed camps on both sides of the pond will ensure that standards globalisation is a long way off.
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